Oxygen mask for pressure breathing



May 8, l951 w. A. WILDHACK 2,551,653

OXYGEN MASK PRESSURE BREATHING Filed Feb. 13, 1946 William A Wild/JOCKPatented May 8, 1951 William A. Wildhack, Arlington, Va.

Application February 13, 1946, Serial No. 647,410

16 Claims.

(Granted under the act of March 3, 1883, as

This invention relates to breathing masks and more particularly tooxygen masks having valve systems for pressure breathing.

This invention may be found of value not only in the field ofaeronautics, where it may become necessary for an aviator to use oxygen,but also in the administration of other therapeutic gases including air,in conditions where intra-tracheal or intra-pulmonary pressures areindicated, as, for example, the relief of asthmatic choking, pulmonaryedema, or unrelieved pressure on the middle ear.

Accordingly, it is a primary object of this invention to provide a newand improved breathing mask.

Another object of the present invention is to provide a new and improvedvalve system in'oxygen masks for pressure breathing.

Another object is to provide an efficient and automatically adjustablebalanced valve for exhausting the expired gases in a pressure oxygensupplied gas mask.

Other and more specific objects will appear in the following detaileddescription of one illustrative form of device built in accordance withthe present invention, having reference to the accompanying drawingswherein:

Fig. l is a partly diagrammatic illustration of a preferred embodimentof the invention; and

Fig. 2 is a perspective view of this embodiment of a gas maskincorporating the novel balanced valve system of the invention.

Referring now to the drawings for a more complete understanding of theinvention, in which like reference characters are used throughout todesignate like parts, and in particular to Fig. 2 thereof, the maskgenerally designated 23 is observed to have an inlet portion I!)connected by duct portion II to a conduit 6 which it is understood isconnected to a suitable source of gas under pressure, not shown. Thecollar I2 of conduit 6 slips over the neck of duct portion I I, Fig. 1,forming a substantially hermetical seal therewith. The mask includes anasal passage portion 8.

Particular reference is made now to Fig. 1, a cross sectional view of amask similar to that of Fig. 2. The duct I8 disposed within theaforementioned nasal passage portion 9 conducts gas under pressure frominlet chamber I to a check or one-way valve 8 mounted in a base I3,which is preferably composed of rubber, and is located in wall 24, thedirection of gas flow being indicated by the arrows. Gas, after passingthrough valve 8, is breathed in by the person wearing the mask.

The mask has an exhaust valve mounted within aperture 20 in a centralsupporting portion thereof. The valve comprises a housing generallydesignated by the reference numeral 4, having an annular recessedportion I9 for receivamended April 30, 1928; 370 O. G. 757) ing the lip2|, and being maintained in place thereby. Around the periphery of thehousing 4 are exhaust apertures 22 for the escape of used gases intoorifice portion I6 and thence from vent II, Fig. 2, and the housing hasa short pipe portion 1 extending through hole or aperture I I. Means,not shown, may be provided for insuring that the pipe portion I forms ahermetical seal with the wall of the hole I4 through which it extends.

Disposed within the housing 4 is a cell or bellows generally designated3, having flexible wall portion 5, and having a lip 2, which, when thebellows is expanded, presses against the adjacent lip I of the housing,forming a substantially hermetical seal therewith.

In the operation of the above described apparatus, the pressure of gasesbreathed out by the person wearing the mask causes the bellows tocontract, and the gases escape through the opening thereby causedbetween aforementioned lips I and 2, the direction of movement of thisgas being indicated by the arrows within the housing, Fig. 1.

The areas of the lip I, and of the lip or lid 2 of the compensating cell3, are so adjusted that when the same pressure is applied to both sidesof the valve it remains closed with a slight force; but when thepressure on the bottom of the valve (or the upper side as viewed inFig. 1) exceeds the pressure in cell 3 by a few tenths of an inch ofwater, the valve opens.

To make possible an increase in mask pressure without a simultaneousincrease in the compensating cell pressure, which would prevent thevalve opening, the aforementioned inlet check valve 8 is installed inthe mask near the region 01 the duct I8 designated I0, terminating theaforementioned inlet duct I8 from the breathing tube 6.

In the manufacture of balanced valves of the type herein employed, itmay be preferable to use an integrally formed bellows or a simplediaphragm. Where a bellows is employed, it is desirable that theefiective area of the bellows wall should not change too much with thevalve opening, and that the bellows be not too stiff. It may bedesirable to use a light spring, not shown, for urging the valve closed,or to omit the mechanical spring if the initial compression of thebellows or other pressure responsive element provides some closing forceon the lip which controls the valve opening. The dimensions of the frameor housing 4 may, of course, be varied to suit the mask; the diameter ofthe valve itself should be adequate to permit rapid exhalation withoutexcessive resistance.

In the design of the mask, the relation between the excess pressure inthe mask and the rate of exhaust flow depends on and may be controlledin various ways by several factors; the differential or unbalanced areaaffected by pressures on the two sides of the valve; the spring loading,if any; the annular area of the valve lid or lip outside the valve seatarea; the clearance between the valve lid and the adjacent portions ofhousing 4; and the position and area of the exhaust vents.

The apparatus of the subject invention is especially well adapted foruse where the delivery pressure from the oxygen pressure regulator, notshown, is very small or even slightly negative with respect to theambient atmosphere. In this condition, which is frequently employed inaeronautics, the regulator is adjusted not for pressure breathing, butonly to supply oxygen upon demand, 1. e., upon a slight suction. Thedifferential area acted upon by the suction tends to open the valve, andit is desirable to provide a mechanical loading, not shown, (e. g., aspring, or resilience of the pressure responsive element), sufficient tohold the valve closed under the operating suction.

In the construction of the apparatus, the check valve 8 shouldpreferably be of a type which inakes a positive seal; leakage may causethe pressure in the delivery tube and compensating cell to build up,preventing the opening of the balanced exhaust valve. A rubber flapvalve,

with a slight positive opening pressure, is indicated as probably thebest type.

The above described apparatus, then, embodies the aforedescribedadvantages of the invenit significantly, since it is connected to themuch larger volume of the delivery tube and regulator, and theregulator, not shown, preferably has an elastic wall.

Obvio ly many modifications and variations of the present invention arepossible in the light of the above teachings It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

This invention may be manufactured and used by or for the Government ofthe United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A pressure breathing gas mask comprising a suitable casing having anopening for applica tion to the face of the breather and gas inlet andoutlet passages, a check valve in said inlet opening inwardly and abalanced valve comprising a bellows having a flexible wall in saidoutlet responsive to a pressure differential between the pressure insaid inlet passage and the pressure in said outlet.

2. A gas mask having an inlet and outlet, a delivery passage connectedto said inlet, a check valve in said inlet opening inwardly, and abalanced valve comprising a bellows having a flexible wall in saidoutlet responsive to pressure in said delivery passage for freelyopening whenever the pressure in the gas mask is slightly raised overthat in the delivery passage.

3. A gas mask having a single breathing chamber with a delivery passageand an exhaust passage, a check valve in said delivery passage and apressure controlled exhaust valve in said exhaust passage, a pressurecell comprising a bellows having a flexible wall for normally closingsaid exhaust valve in response to pressure in said delivery passage,said bellows providing light resilient means for urging the exhaustvalve into a closed position whereby the valve will maintain its seatwhen the pressures are equalized and will open upon a slight increase inthe pressure in the gas mask over that in the delivery passage.

4. In a pressure ga mask having a gas supply conduit, an outlet for theexhaled gases to the atmosphere having a balanced valve comprising abellows having a flexible wall, means for applying the pressure in thesupply conduit to said bellows to urge said valve in a closingdirection, said flexible wall normally furnishing an additional lightresilient force to said valve in the closing direction.

5. In a pressure gas mask, a breathing chamber for direct communicationwith the mouth and nose of the breather, an inlet chamber communieatingwith the gas supply, an outlet chamber communicating with theatmosphere, an inlet check valve between said inlet chamber and saidbreathing chamber normally held closed by a light spring, an outletvalve between said breathing chamber and said outlet chamber normallyheld closed by light resilient means, said resilient means comprising abellows having a flexible wall, and additional closing pressure meansconnected to said inlet chamber, whereby to maintain the differentialopening pressure of said outlet valve substantially constant regardlessof pressure variations in said inlet chamber.

6. In a pressure gas mask, a breathin chamber, an inlet chamberconnected to the gas supply, an outlet chamber opening into theatmosphere, an inlet check valve between said inlet chamber and saidbreathing chamber, an outlet valve between said breathing chamber andsaid outlet chamber normally held closed by light resilient means andhaving a movable valve element comprising an end wall of an expandablechamber connected to the inlet chamber, said end wall being exposed onits inner side to the pressure in the inlet chamber and on its outerside to the pressure in the breathing chamber, said resilient meanscomprising a bellows having a flexible Wall.

7. In a pressure gas mask, a breathing chamber, an inlet chamberconnected to the gas supply, an outlet chamber opening into theatmosphere, an inlet check valve between said inlet chamber and saidbreathing chamber, and an outlet valve between said breathing chamberand said outlet chamber normally held closed by light resilient meansand having a movable valve element exposed on its outer side to thepressure in the inlet chamber and on its inner side to the pressure inthe breathing chamber, said resilient means including a bellows having aflexible wall, the area of the movable element exposed to the pressurein the inlet chamber being slightly greater than that exposed to thebreathing chamber when the valve is closed, whereby equal pressures onopposite sides of said valve will normally maintain it in the closedposition.

8. A pressure breathing gas mask comprising a suitable casing having achamber for application to the face of the breather and gas outlet andinlet passages connecting with said chamber, a check valve mounted insaid inlet passage and opening inwardly while the pressure in said inletpassage exceeds the pressure in said chamber, and a balanced valve insaid outlet passage Iresponsive to a pressure dillerential between thepressure in said chamber and the pressure in said inlet passage.

9. A gas mask having means forming a breath ing chamber and an inlet andoutlet for the chamber, means forming a gas delivery connected to saidinlet, a check valve in inlet opening inwardly into the chamber, and abalanced valve in said outlet responsive to a pressure differentialbetween a first pressure in breathing chamber and a second pressure insaid gas delivery passage, said balanced val e constructed and arrangedto open outwardly from the breathing chamber when the first pressureexceeds the second pressure by a prede-- termined amount.

10. A mask according to claim 9 wherein said balanced valve comprises aflexible member of predetermined dimensions whereby the relative areasthereof exposed to the first and second pressures provide for valveoperation responsive to the pressure differential.

11. A gas mask comprising a suitable casing having a chamber forapplication to the face of the breather and gas outlet and inletpassages connecting with said chamber, a check valve mounted in saidinlet passage and opening inwardly while the pressure in said inletpassage exceeds the pressure in said chamber, and a differentialpressure operated balanced valve in said outlet passage andcommunicating with said inlet passage, said balanced valve comprising amow able member of predetermined dimensions whereby the relative areasthereof exposed to the pressures in the chamber and inlet passageprovide for opening the balanced valve outwardly to permit the escape ofgas when the pressure diiferential reaches at least a predeterminedvalue.

12. A gas mask having a single breathing chamber with a delivery passageand an exhaust passage, a check valve in said delivery passage and adifferential pressure controlled exhaust valve in said exhaust passage,means connecting said exhaust valve with the delivery passage, saidexhaust valve including light resilient means for urging the exhaustvalve into a closed position whereby the exhaust valve will maintain itsseat while the pressures in the chamber and delivery passage areequalized and will open to permit the escape of gas upon a slightincrease in the pressure in the breathing chamber over that in thedelivery passage.

13. In a pressure gas mask having a gas supply conduit, an outlet forthe exhaled gases to the atmosphere having a balanced valve connected tothe gas supply conduit and responsive to a pressure differential betweenthe pressure in the mask and the pressure in the supply conduit, saidbalanced valve including means for applying the pressure in the supplyconduit to the outside of said valve to urge said valve in a closingdirection, said balanced valve including means normally furnishing anadditional light resilient force to said valve in the closing direction.

14. In a pressure gas mask for use with a gas supply, means forming abreathing chamber for direct communication with the mouth and nose ofthe breather, an inlet chamber communicating with the gas supply, and anoutlet chamber communicating with the atmosphere; an inlet check val ebetween said inlet chamber and said breathing chamber normally heldclosed by a light spring; and a differential pressure operoutlet valvebetween said breathing chamber and said outlet chamber normally heldclosed b light resilient means, said outlet valve includi additionalclosing pressure means connected to said inlet chamber whereby tomaintain the differential opening pressure of said outlet valvesubstantially constant regardless of pressure variations in said inletchamber.

15. In a pressure gas mask for use with a gas supply, means forming abreathing chamber, an 'nlet chamber connected to the gas supply, and anoutlet chamber opening into the atmosphere; an inlet check valve betweensaid inlet chamber and said breathing chamber; and a diiferential outletvalve between said breathing chamber and said outlet chamber normallyheld closed by light resilient means and having a movable valve elementexposed on its inner side to the pressure in the inlet chamber and onits outer side to the pressure in the breathing chamber; and adapted toopen the valve to permit the escape of gas when the pressure in thebreathing chamber exceeds the pressure in the inlet chamber by apredetermined amount.

16. In a pressure gas mask for use with a gas supply, means forming abreathing chamber, an inlet chamber connected to thegas supply, and anoutlet chamber opening into the atmosphere; an inlet check valve betweensaid inlet chamber and said breathing chamber; and a differential outletvalve between said breathing chamber and said outlet chamber normallyheld closed by light resilient means and having a movable valve elementexposed on its outer side to the pressure in the inlet chamber and onits inner side to the pressure in the breathing chamber, the area of themovable element exposed to the pressure in the inlet chamber being onlyslightly greater than that exposed to the breathing chamber when thevalve is closed, whereby quick opening is obtained when exhaling in thebreathing chamber increases the pressure therein over the pressure inthe inlet chamber.

WILLIAM A. WILDHACK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 680,419 Schaefier Aug. 17, 19011,503,970 Guillemard Sept. 16, 1924 1,509,319 Saunier Sept. 23, 19261,691,648 Drager Nov. 17, 1928 2,168,695 Asari Aug. 8, 1939 2,453,475Tobias Nov. 9, 1948 FOREIGN PATENTS Number Country Date 292,531 GreatBritain Mar. 7, 1929

